Spin-valve magnetoresistive element

ABSTRACT

A spin-valve magnetoresistive element includes a hard bias layer formed on a pinned magnetic layer with a non-magnetic layer therebetween, and thus the magnetic field from the hard bias layer is efficiently applied into a free magnetic layer. Also, the pinned magnetic layer is not influenced by the hard bias layer because of the interposition of the non-magnetic layer. Accordingly, the pinned magnetic layer and the free magnetic layer are properly put into single magnetic domain states, and thus, Barkhausen noise is reduced and satisfactory micro-track-asymmetry can be obtained.

This is a Divisional of application Ser. No. 09/081,955, filed May 19,1998, which is currently pending.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a spin-valve magnetoresistive elementin which electrical resistance changes in response to the relationshipbetween the magnetic direction of a pinned magnetic layer and themagnetic direction of a free magnetic layer which is influenced by anexternal magnetic field, and more particularly relates to a spin-valvemagnetoresistive element in which the magnetizations of a pinnedmagnetic layer and a free magnetic layer are properly put into singlemagnetic domain states so that Barkhausen noise is reduced andsatisfactory micro-track-asymmetry can be obtained.

2. Description of the Related Art

FIG. 4 is a sectional view which shows the conventional structure of aspin-valve magnetoresistive element (spin-valve magnetoresistive head)which detects a recording magnetic field from a recording medium such asa hard disk.

This spin-valve magnetoresistive element includes an antiferromagneticlayer 1, a pinned magnetic layer 2, a non-magnetic electricallyconductive layer 3, and a free magnetic layer 4 deposited in that order,and hard bias layers 5 and 5 formed on both sides thereof.

Generally, an iron-manganese (Fe--Mn) alloy film or a nickel-manganese(Ni--Mn) alloy film is used for the antiferromagnetic layer 1, aniron-nickel (Fe--Ni) alloy film is used for the pinned magnetic layer 2and the free magnetic layer 4, a copper (Cu) film is used for thenon-magnetic electrically conductive layer 3, and a cobalt-platinum(Co--Pt) alloy film or the like is used for the hard bias layers 5 and5. Also, an underlying layer 6 and a protective layer 7 are composed ofa non-magnetic material, for example, tantalum (Ta).

As shown in the drawing, the antiferromagnetic layer 1 and the pinnedmagnetic layer 2 are formed in contact with each other, the pinnedmagnetic layer 2 is put into a single magnetic domain state in the Ydirection by an exchange anisotropic magnetic field caused by exchangecoupling at the interface between the pinned magnetic layer 2 and theantiferromagnetic layer 1, and the magnetic direction is pinned in the Ydirection. The exchange anisotropic magnetic field occurs at theinterface between the antiferromagnetic layer 1 and the pinned magneticlayer 2 by annealing (heat treatment) while applying the magnetic fieldin the Y direction.

Also, the magnetic direction of the free magnetic layer 4 is aligned inthe X direction under the influence of the hard bias layers 5 and 5which are magnetized in the X direction.

A method for fabricating the spin-valve magnetoresistive element shownin FIG. 4 includes the steps of depositing six layers from theunderlying layer 6 to the protective layer 7, scraping the sides of thesix layers so as to have inclined edges in the etching process, forexample, by ion-milling, and then, depositing hard bias layers 5 and 5on opposite sides of the six layers.

In the spin-valve magnetoresistive element, a stationary electriccurrent (sensing current) is applied from electrically conductive layers8 and 8 formed on the hard bias layers 5 and 5 into the pinned magneticlayer 2, the non-magnetic electrically conductive layer 3, and the freemagnetic layer 4. The driving direction of a recording medium such as ahard disk is in the Z direction, and if a magnetic field leaked from therecording medium is applied in the Y direction, the magnetization of thefree magnetic layer 4 changes from the X direction to the Y. Because ofthe relationship between the change in the magnetic direction in thefree magnetic layer 4 and the pinned magnetic direction of the pinnedmagnetic layer 2, the electrical resistance changes, and the magneticfield leaked from the recording medium can be detected by the voltagechange based on the change in the electrical resistance.

In the conventional spin-valve magnetoresistive element shown in FIG. 4,however, there are the following problems.

As described above, although the magnetization of the pinned magneticlayer 2 is pinned in the Y direction (shown in the drawing), the hardbias layers 5 and 5 magnetized in the X direction are provided on bothsides of the pinned magnetic layer 2. Therefore, the magnetization of,in particular, both ends of the pinned magnetic layer 2 is influenced bythe bias magnetic field from the hard bias layers 5 and 5, and is notpinned in the Y direction (shown in the drawing).

That is, in the spin-valve magnetoresistive element, it is preferablethat the magnetization of the pinned magnetic layer 2 and themagnetization of the free magnetic layer 4 be put into single magneticdomain states in the Y direction and in the X direction, respectively,and that the magnetization of the pinned magnetic layer 2 be orthogonalto that of the free magnetic layer 4 in the entire region. However, themagnetization relationship between the pinned magnetic layer 2 and thefree magnetic layer 4 around both ends is not orthogonal because themagnetization of the pinned magnetic layer 2 is not pinned in the Ydirection, and satisfactory micro-track-asymmetry cannot be obtainedaround both ends. The word "micro-track-asymmetry" means the verticalasymmetry of the regenerated output waveform measured in a track widthwhich is smaller than the real track width.

If the regenerated output value has the same height at every part whenmicro-track-asymmetry is measured, the micro-track-asymmetry isconsidered to be in a satisfactory condition. However, when themicro-track-asymmetry is measured around both ends of the pinnedmagnetic layer 2 and the free magnetic layer 4 shown in FIG. 4, theregenerated output value has non-uniform height. That is, themicro-track-asymmetry is in the deteriorated condition, which makes itdifficult to detect the track position accurately and easily leads to aservo error.

Also, in addition to the above-mentioned problem, in the spin-valvemagnetoresistive element shown in FIG. 4, the hard bias layers 5 and 5provided on opposite sides of the free magnetic layer 4 aresubstantially thin, and thus, a sufficient bias magnetic field cannot beapplied from the hard bias layers 5 and 5 to the free magnetic layer 4in the X direction. Accordingly, the magnetic direction of the freemagnetic layer 4 is not stabilized easily in the X direction, andBarkhausen noise easily occurs.

SUMMARY OF THE INVENTION

The present invention overcomes the problems noted above with respect tothe related art. It is an object of the present invention to provide aspin-valve magnetoresistive element in which a sufficient bias magneticfield is applied from a hard bias layer into a free magnetic layer whilethe hard bias layer does not influence the magnetization of a pinnedmagnetic layer so that the magnetizations of the pinned magnetic layerand the free magnetic layer are properly put into single magnetic domainstates in given directions, and thus satisfactory micro-track-asymmetrycan be obtained, and also Barkhausen noise can be reduced.

In a spin-valve magnetoresistive element in accordance with the presentinvention, a pinned magnetic layer is formed on an antiferromagneticlayer, wherein the magnetic direction is pinned by an exchangeanisotropic magnetic field between the pinned magnetic layer and theantiferromagnetic layer. A non-magnetic electrically conductive layerand a free magnetic layer are deposited thereon, and also, a bias layerfor aligning the magnetic direction of the free magnetic layer in thedirection perpendicular to the magnetic direction of the pinned magneticlayer, and an electrically conductive layer for applying a sensingcurrent into the pinned magnetic layer, the non-magnetic electricallyconductive layer, and the free magnetic layer are provided. Theantiferromagnetic layer and the pinned magnetic layer extend to theregions beside both sides of the non-magnetic electrically conductivelayer and the free magnetic layer. The bias layer and an electrode layerare deposited on the pinned magnetic layer in the regions beside bothsides with a non-magnetic layer therebetween.

FIG. 1 can be referred to as an embodiment of the present invention.

Also, it is preferable that the non-magnetic layer is composed of ametal layer having a body-centered cubic structure and (100)orientation.

Also, in a spin-valve magnetoresistive element in accordance with thepresent invention, a pinned magnetic layer is formed on anantiferromagnetic layer, wherein the magnetic direction is pinned by anexchange anisotropic magnetic field with the antiferromagnetic layer. Anon-magnetic electrically conductive layer and a free magnetic layer aredeposited thereon, and also, a bias layer for aligning the magneticdirection of the free magnetic layer in the direction perpendicular tothe magnetic direction of the pinned magnetic layer, and an electricallyconductive layer for applying a sensing current into the pinned magneticlayer, the non-magnetic electrically conductive layer, and the freemagnetic layer are provided. The antiferromagnetic layer, the pinnedmagnetic layer, and the non-magnetic electrically conductive layerextend to the regions beside both sides of the free magnetic layer, andthe bias layer and an electrode layer are deposited on the non-magneticelectrically conductive layer in the regions beside both sides.

FIG. 2 can be referred to as an embodiment of the present invention.

It is preferable that a non-magnetic metal layer having a body-centeredcubic structure and (100) orientation is formed between the non-magneticelectrically conductive layer and the bias layer.

In the present invention, Cr, Ti, Mo, or W₅₀ Mo₅₀ can be presented asthe non-magnetic metal layer having a body-centered cubic structure and(100) orientation.

Also, in a spin-valve magnetoresistive element in accordance with thepresent invention, a pinned magnetic layer is formed on anantiferromagnetic layer, wherein the magnetic direction is pinned by anexchange anisotropic magnetic field between the pinned magnetic layerand the antiferromagnetic layer. A non-magnetic electrically conductivelayer and a free magnetic layer are deposited thereon, and also, a biaslayer for aligning the magnetic direction of the free magnetic layer inthe direction perpendicular to the magnetic direction of the pinnedmagnetic layer, and an electrically conductive layer for applying asensing current into the pinned magnetic layer, the non-magneticelectrically conductive layer, and the free magnetic layer are provided.A ferromagnetic layer having a body-centered cubic structure and (100)orientation is formed on the free magnetic layer beside both ends of acutout section provided between the ferromagnetic layer, and the biaslayer and an electrode layer are deposited on the ferromagnetic layer.

FIG. 3 can be referred to as an embodiment of the present invention.

It is preferable that the ferromagnetic layer be composed of an Fe--X(X=Rh, Cr, Ti, Zr, Hf, V, Nb, Ta, Mn, Ru, Pd, Pt) alloy or an Fe--Co--Nialloy.

In accordance with the present invention, as shown in FIG. 1 and FIG. 2,since both sides of a free magnetic layer 4 are scraped so as to haveinclined edges, a hard bias layer 5 is formed on a pinned magnetic layer2 with a non-magnetic layer (a non-magnetic layer 9 in FIG. 1, and anon-magnetic electrically conductive layer 3 in the T2 region in FIG. 2)therebetween, the thick parts of the hard bias layer 5 which generates astrong bias magnetic field are provided on opposite sides of the freemagnetic layer 4, and thus a sufficient bias magnetic field is appliedfrom the hard bias layer 5 into the free magnetic layer 4. Also, thehard bias layer 5 is formed apart from the pinned magnetic layer 2,without lying on opposite sides of the pinned magnetic layer 2, andtherefore, the magnetic field from the hard bias layer 5 is not appliedinto the pinned magnetic layer 2, and is intensively applied into thefree magnetic layer 4 with efficiency.

The non-magnetic layer 9 in FIG. 1 is composed of a metal layer having abody-centered cubic structure and (100) orientation, and preferably, inFIG. 2, the metal layer is formed on the non-magnetic electricallyconductive layer 3 in the T2 region. In such a structure, a coerciveforce Hc and a squareness ratio S of the hard bias layer 5 increase andthe bias magnetic field from the hard bias layer 5 increases.

Because of the structure described above, the free magnetic layer 4shown in FIG. 1 and FIG. 2 is properly put into a single magnetic domainstate in the direction (the X direction in the drawing) which isorthogonal to the magnetic direction of the pinned magnetic layer 2 inthe entire region.

Also, since a non-magnetic layer is formed below the hard bias layer 5,a ferromagnetic coupling does not occur between the hard bias layer andthe pinned magnetic layer 2, and the magnetization from the hard biaslayer 5 is shielded by the non-magnetic layer and does not influence themagnetization of the pinned magnetic layer 2.

As described above, the pinned magnetic layer 2 in accordance with thepresent invention is not influenced by the magnetic field from the hardbias layer 5, differing from the conventional pinned magnetic layer 2.Therefore, the magnetization of the pinned magnetic layer 2 shown inFIG. 1 and FIG. 2 is pinned in a given direction (the Y direction in thedrawing) in the entire region. Also, in contrast with the related art,the pinned magnetic layer 2 and the antiferromagnetic layer 1 extend tothe T1 region (in FIG. 1) and the T2 region (in FIG. 2) below the hardbias layer 5. Thus, the pinned magnetic layer 2 is pinned in the Ydirection in a wider range than the track width, enabling furtherprevention in fluctuation of the magnetization of the pinned magneticlayer 2 owing to the magnetic field from a magnetic recording medium.

Also, in FIG. 3, a hard bias layer 5 is formed on a free magnetic layer4 with a ferromagnetic layer 10 therebetween, beside both ends of acut-out section (in the T3 region).

Because of the ferromagnetic coupling at the interface between the hardbias layer 5 and the ferromagnetic layer 10 and at the interface betweenthe ferromagnetic layer 10 and the free magnetic layer 4 in the T3region, the free magnetic layer 4 is easily and properly put into asingle magnetic domain state in the direction (the X direction) which isorthogonal to the magnetization of the pinned magnetic layer 2.

Also, since the hard bias layer 5 is formed apart from the pinnedmagnetic layer 2, the magnetic field leaked from the hard bias layer 5does not influence the magnetization of the pinned magnetic layer 2, andthus, the magnetization of the pinned magnetic layer 2 in FIG. 3 isproperly pinned in a given direction (the Y direction in the drawing) inthe entire region.

As described above, in accordance with the present invention, the pinnedmagnetic layer 2 and the free magnetic layer 4 are properly put intosingle magnetic domain states in given directions (orthogonal to eachother) in the entire region, and thus satisfactory micro-track-asymmetrycan be obtained, resulting in the prevention of a servo error. Also,since the pinned magnetic layer 2 and the free magnetic layer 4 areproperly put into single magnetic domain states, Barkhausen noise doesnot easily occur.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view which shows the structure of a spin-valvemagnetoresistive element as a first embodiment of the present invention;

FIG. 2 is a sectional view which shows the structure of a spin-valvemagnetoresistive element as a second embodiment of the presentinvention;

FIG. 3 is a sectional view which shows the structure of a spin-valvemagnetoresistive element as a third embodiment of the present invention;and

FIG. 4 is a sectional view which shows the structure of a conventionalspin-valve magnetoresistive element.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a sectional view which shows the structure of a spin-valvemagnetoresistive element as a first embodiment of the present invention.The sectional view is taken in the central part of the element whichstretches in the X direction.

The spin-valve magnetoresistive head is provided, for example, on theend of the trailing side of a levitated slider in a hard disk drive fordetecting a recording magnetic field of a hard disk or the like. Amagnetic recording medium such as a hard disk moves in the Z directionwhile the magnetic field leaked from the magnetic recording medium isdirected in the Y direction.

An underlying layer 6 formed in the lowest part shown in FIG. 1 iscomposed of a non-magnetic material, for example, tantalum (Ta). Anantiferromagnetic layer 1 and a pinned magnetic layer 2 are deposited onthe underlying layer 6. The antiferromagnetic layer 1 and the pinnedmagnetic layer 2 under deposition are heat-treated in a magnetic fieldhaving a given dimension, and thus an exchange anisotropic magneticfield is obtained in the interface between both layers, and the magneticdirection of the pinned magnetic layer 2 is put into a single magneticdomain state and pinned in the Y direction.

In accordance with the present invention, a platinum-manganese (Pt--Mn)alloy is used for the antiferromagnetic layer 1. The Pt--Mn alloy hasexcellent properties as an antiferromagnetic material because ofsuperior corrosion resistance to an Fe--Mn alloy or the like, and a highblocking temperature, and also because an exchange anisotropic magneticfield can be obtained at a heat-treatment temperature of 230° C. (aheating temperature at the hard baking process of an ultravioletradiation curing resin) or less.

Instead of the Pt--Mn alloy, a palladium-manganese (Pd--Mn) alloy, aPt--Mn--X (X=Ni, Pd, Rh, Ru, Ir, Cr, Co) alloy, or an alloy which hasbeen used such as Ni--Mn or Fe--Mn may be used for the antiferromagneticlayer 1.

The pinned magnetic layer 2 is composed of a nickel-iron (Ni--Fe) alloy,cobalt (Co), an iron-cobalt (Fe--Co) alloy, an Fe--Co--Ni alloy, or thelike.

A non-magnetic electrically conductive layer 3 having a low electricalresistance, composed of, for example, copper (Cu), is formed on thepinned magnetic layer 2, and a free magnetic layer 4 and a protectivelayer 7 composed of Ta or the like are further deposited thereon. Thefree magnetic layer 4 is composed of the magnetic material used for thepinned magnetic layer 2.

Next, a method for fabricating the layered structure including from theunderlying layer 6 to the protective layer 7 will be described asfollows.

After depositing the six layers from the underlying layer 6 to theprotective layer 7 by sputtering, the non-magnetic electricallyconductive layer 3, the free magnetic layer 4 and the protective layer 7remain in the central part in the X direction while both sides (in theT1 regions) thereof are removed in the etching process, for example, byion-milling. At this stage, although the pinned magnetic layer 2 mayalso be affected by etching and scraped off to a certain depth, it ispreferable that the pinned magnetic layer 2 is not scraped off as muchas possible. By keeping a little portion of the non-magneticelectrically conductive layer 3 on the pinned magnetic layer 2 in the T1regions when the etching treatment is performed, the pinned magneticlayer 2 is not substantially affected by etching and the scrapings canbe minimized.

As shown in FIG. 1, a non-magnetic layer 9 is deposited on the pinnedmagnetic layer 2 in the T1 regions and on the inclined edges of thenon-magnetic electrically conductive layer 3, the free magnetic layer 4,and the protective layer 7. Also, a hard bias layer 5 and anelectrically conductive layer 8 are deposited on the non-magnetic layer9.

In accordance with the present invention, it is preferable that thenon-magnetic layer 9 be composed of a metal layer having a body-centeredcubic structure (bcc) and (100) orientation.

As the metal layer having a body-centered cubic structure as the crystalstructure and (100) orientation, chromium (Cr), titanium (Ti),molybdenum (Mo), tungsten (W), or W₅₀ Mo₅₀ (The suffix 50 means atomicpercent.) can be used. The non-magnetic layer 9 may be formed with oneof these materials or with a mixture of at least two.

The hard bias layers 5 and 5 are composed of, for example, acobalt-platinum (Co--Pt) alloy or a cobalt-chromium-platinum(Co--Cr--Pt) alloy.

If the hard bias layer 5 composed of a Co--Pt alloy or the like isformed on the non-magnetic layer 9 composed of Cr or the like which hasa body-centered cubic structure and (100) orientation, a coercive forceHc and a squareness ratio S corresponding to residual magnetization(Br)/saturation magnetic flux density (Bs) of the hard bias layer 5increase. As a result, a bias magnetic field generating from the hardbias layer 5 increases.

Also, in accordance with the present invention, as shown in FIG. 1,since the hard bias layer 5 is formed on the pinned magnetic layer 2 inthe T1 region with the non-magnetic layer 9 therebetween, the hard biaslayer 5 formed on opposite sides of the free magnetic layer 4 is thickerin comparison with the related art, and therefore, a sufficient biasmagnetic field is applied from the hard bias layer 5 to the freemagnetic layer 4. Also, the hard bias layer 5 is not present on oppositesides of the pinned magnetic layer 2 and is formed apart from the pinnedmagnetic layer 2, and thus, the magnetic field from the hard bias layer5 is not applied into the pinned magnetic layer 2, and is intensivelyapplied into the free magnetic layer 4 with efficiency.

Accordingly, the free magnetic layer 4 in accordance with the presentinvention is properly put into a single magnetic domain state in the Xdirection in the entire region.

Also, since the hard bias layer 5 is formed on the pinned magnetic layer2, not directly, but with the non-magnetic layer 9 therebetween,ferromagnetic coupling does not occur between the pinned magnetic layer2 and the hard bias layer 5. Because of the presence of the non-magneticlayer 9, the magnetization of the hard bias layer 5 is shielded by thenon-magnetic layer 9, and does not influence the magnetization of thepinned magnetic layer 2. As described above, the pinned magnetic layer 2is not influenced by the hard bias layer 5, and thus, the pinnedmagnetic layer 2 is properly put into a single magnetic domain state inthe Y direction in the entire region.

Differing from the related art, the pinned magnetic layer 2 and theantiferromagnetic layer 1 extend to the T1 region below the hard biaslayer 5. Thus, the pinned magnetic layer 2 is pinned in the Y directionin a wider range than the track width, enabling further prevention influctuation of the magnetization of the pinned magnetic layer 2 causedby the magnetic field from a magnetic recording medium.

Also, in accordance with the present invention, even if the non-magneticlayer 9 is composed of a non-magnetic material, for example, SiO₂,instead of the metal layer having a body-centered cubic structure and(100) orientation, the magnetization of the pinned magnetic layer 2 andthe free magnetic layer 4 can be aligned in the proper direction.

FIG. 2 is a variation to the spin-valve magnetoresistive element as anembodiment of the present invention shown in FIG. 1. A magneticrecording medium moves in the Z direction while the magnetic fieldleaked from the magnetic recording medium is directed in the Ydirection.

In the spin-valve magnetoresistive element shown in FIG. 2, anunderlying layer 6, an antiferromagnetic layer 1, a pinned magneticlayer 2, a non-magnetic electrically conductive layer 3, a free magneticlayer 4, and a protective layer 7 are deposited in that order from thebottom, in the same way as in the spin-valve magnetoresistive elementshown in FIG. 1.

The pinned magnetic layer 2 is put into a single magnetic domain stateand pinned in the Y direction by the exchange anisotropic coupling atthe interface with the antiferromagnetic layer 1.

As shown in FIG. 2, the free magnetic layer 4 and the protective layer 7remain in the central part in the X direction, and the underlying layer6, the antiferromagnetic layer 1, the pinned magnetic layer 2, and thenon-magnetic electrically conductive layer 3 further extend to theregions beside both sides in the X direction (T2 regions).

A hard bias layer 5 is deposited on the non-magnetic electricallyconductive layer 3 in the T2 regions and on the inclined planes of thefree magnetic layer 4 and the protective layer 7. Also, an electricallyconductive layer 8 is formed on the hard bias layer 5. The hard biaslayer 5 is put into a single magnetic domain state in the X direction,and the free magnetic layer 4 is put into a single magnetic domain statein the X direction by the bias magnetic field from the hard bias layer5.

In comparison with the spin-valve magnetoresistive element shown in FIG.1, in the spin-valve magnetoresistive element shown in FIG. 2, thenon-magnetic electrically conductive layer 3 extends to the regions (T2regions) beside both sides of the free magnetic layer 4. That is, inFIG. 2, the non-magnetic electrically conductive layer 3 in the T2regions interposes between the hard bias layer 5 and the pinned magneticlayer 2, and thus, ferromagnetic coupling does not occur between thehard bias layer 5 and the pinned magnetic layer 2, and since themagnetic field leaked from the hard bias layer 5 is shielded by thenon-magnetic electrically conductive layer 3, the leaked magnetic fielddoes not influence the magnetization of the pinned magnetic layer 2.

Accordingly, the pinned magnetic layer 2 is properly put into a singlemagnetic domain state and pinned in the Y direction in the entireregion.

Also, as shown in FIG. 2, since the hard bias layer 5 is formed on thenon-magnetic electrically conductive layer 3, as is the free magneticlayer 4, the thick parts of the hard bias layer 5 which generate astrong magnetic field are formed on both sides of the free magneticlayer 4, and thus, the free magnetic layer 4 is properly put into asingle magnetic domain state in the X direction. Also, the hard biaslayer 5 is not present on both sides of the pinned magnetic layer 2 andis formed apart from the pinned magnetic layer 2, and thus, the magneticfield from the hard bias layer 5 is not applied into the pinned magneticlayer 2, and is intensively applied into the free magnetic layer 4 withefficiency.

Also, in the spin-valve magnetoresistive element shown in FIG. 2, ametal layer composed of, for example, Cr, having a body-centered cubicstructure and (100) orientation described with reference to FIG. 1 maybe deposited on the non-magnetic electrically conductive layer 3 in theT2 regions and on the inclined edges of the free magnetic layer 4 andthe protective layer 7.

In such a structure, a coercive force Hc and a squareness ratio S of thehard bias layer 5 increase, and the bias magnetic field generating fromthe hard bias layer 5 increases. As a result, the magnetization of thefree magnetic layer 4 is more easily put into a single magnetic domainstate in the X direction.

FIG. 3 is a sectional view which shows the structure of a spin-valvemagnetoresistive element as another embodiment of the present invention.

As shown in the drawing, an underlying layer 6, an antiferromagneticlayer 1, a pinned magnetic layer 2, a non-magnetic electricallyconductive layer 3, and a free magnetic layer 4 are deposited in thatorder from the bottom. The pinned magnetic layer 2 is put into a singlemagnetic domain state by the exchange anisotropic magnetic field at theinterface with the antiferromagnetic layer 1.

A ferromagnetic layer 10, a hard bias layer 5, and an electricallyconductive layer 8 are deposited on the free magnetic layer 4, excludinga cut-out section in the central part, on both sides of the cut-outsection (T3 regions).

A protective layer 7 is formed on the electrically conductive layer 8and on the free magnetic layer 4.

In accordance with the present invention, the ferromagnetic layer 10 isa metal layer having a body-centered cubic structure and (100)orientation, composed of, for example, an Fe--X (X=Rh, Cr, Ti, Zr, Hf,V, Nb, Ta, Mn, Ru, Pd, Pt) alloy or an Fe--Co--Ni alloy.

Next, the mechanism of the single magnetic domain of the free magneticlayer 4 will be described. The hard bias layer 5 is magnetized in the Xdirection in the drawing.

The magnetization of the ferromagnetic layer 10 is put into a singlemagnetic domain state in the X direction by ferromagnetic coupling atthe interface between the ferromagnetic layer 10 and the hard bias layer5.

The magnetization of the free magnetic layer 4 in the T3 region is putinto a single magnetic domain state in the X direction by ferromagneticcoupling at the interface between the free magnetic layer 4 and theferromagnetic layer 10. The magnetization of the free magnetic layer 4in the region excluding the T3 regions (in which the ferromagnetic layer10 is not formed thereon) is gradually magnetized in the X direction bythe magnetization of the free magnetic layer 4 which is put into asingle magnetic domain state in the X direction in the T3 regions, andthus the entire free magnetic layer 4 is properly put into a singlemagnetic domain state in the X direction.

Also, the magnetic field leaked from the hard bias layer 5 directlyflows into the free magnetic layer 4. Since the hard bias layer 5 isformed apart from the pinned magnetic layer 2, the magnetic field fromthe hard bias layer 5 is not applied into the pinned magnetic layer 2and is intensively applied into the free magnetic layer 4 withefficiency. Thus, the free magnetic layer 4 is more easily put properlyinto a single magnetic domain state in the X direction.

Also, in the spin-valve magnetoresistive element shown in FIG. 3, thehard bias layer 5 is formed apart from the pinned magnetic layer 2, andtherefore, the magnetic field leaked from the hard bias layer 5 does notinfluence the magnetization of the pinned magnetic layer 2. The pinnedmagnetic layer 2 is not influenced by the hard bias layer 5, and thus,the pinned magnetic layer 2 is properly put into a single magneticdomain state and pinned in the Y direction in the entire region.

The pinned magnetic layer 2 and the antiferromagnetic layer 1 alsoextend to the T3 region below the hard bias layer 5. Thus, the pinnedmagnetic layer 2 is pinned in the Y direction in a range wider than thetrack width, enabling further prevention in fluctuation of themagnetization of the pinned magnetic layer 2 caused by the magneticfield of a magnetic recording medium.

In the spin-valve magnetoresistive elements as the embodiments describedabove in detail, a stationary electric current (sensing current) isapplied from the electrically conductive layer 8 into the pinnedmagnetic layer 2, the non-magnetic electrically conductive layer 3, andthe free magnetic layer 4, and if the magnetic field from a recordingmedium is applied in the Y direction, the magnetization of the freemagnetic layer 4 changes from the X direction to Y. At this stage,electrons, which transfer from one of the layers among the free magneticlayer 4 and the pinned magnetic layer 2 to the other layer, scatter atthe interface between the non-magnetic electrically conductive layer 3and the pinned magnetic layer 2, or at the interface between thenon-magnetic electrically conductive layer 3 and the free magnetic layer4, and the electrical resistance changes. Thus, the stationary electriccurrent changes, and an output can be detected.

In accordance with the embodiments of the present invention, the pinnedmagnetic layer 2 is properly put into a single magnetic domain state inthe Y direction, and the free magnetic layer 4 is properly put into asingle magnetic domain state in the X direction, and thus themagnetization of the pinned magnetic layer 2 and the magnetization ofthe free magnetic layer 4 are perpendicular to each other in the entireregion, resulting in the prevention of a servo error and the reductionof Barkhausen noise.

In accordance with the present invention described above in detail, byforming a hard bias layer, which applies a bias magnetic field into afree magnetic layer, on a pinned magnetic layer with a non-magneticlayer therebetween, the thick parts of the hard bias layer can be placedadjacent to both sides of the free magnetic layer. Also, in particular,if the non-magnetic layer is composed of a metal layer having abody-centered cubic structure and (100) orientation, the magneticproperties (coercive force and squareness ratio) of the hard bias layercan be enhanced, and the magnetization of the free magnetic layer can beproperly put into a single magnetic domain state in the directionperpendicular to the magnetic direction of the pinned magnetic layer.

Also, by interposing the non-magnetic layer between the hard bias layerand the pinned magnetic layer, ferromagnetic coupling can be prevented,the magnetization of the hard bias layer can be shielded by thenon-magnetic layer, and thus, the pinned magnetic layer is notinfluenced by the magnetization of the hard bias layer. Therefore, themagnetization of the pinned magnetic layer can be properly put into asingle magnetic domain state and pinned in a given direction.

Also, in accordance with the present invention, a ferromagnetic layerhaving a body-centered cubic structure and (100) orientation is formedon the free magnetic layer at a given space, and the hard bias layer isformed on the ferromagnetic layer. Thus, by ferromagnetic coupling, themagnetization of the free magnetic layer can be properly put into asingle magnetic domain state in the direction perpendicular to themagnetic direction of the pinned magnetic layer.

Also, with such a structure, since the hard bias layer can be formedapart from the pinned magnetic layer, the pinned magnetic layer is notinfluenced by the hard bias layer, and therefore, the magnetization ofthe pinned magnetic layer can be properly put into a single magneticdomain state and pinned in a given direction.

As described above, in accordance with the present invention, the pinnedmagnetic layer and the free magnetic layer can be properly put intosingle magnetic domain states in given directions, and thus,satisfactory micro-track-asymmetry can be obtained, a servo error can beprevented, and Barkhausen noise can be reduced.

What is claimed is:
 1. A spin-valve magnetoresistive elementcomprising:an antiferromagnetic layer; a pinned magnetic layer formed onsaid antiferromagnetic layer, a magnetic direction of said pinnedmagnetic layer being pinned by an exchange anisotropic magnetic fieldbetween said pinned magnetic layer and said antiferromagnetic layer; anon-magnetic electrically conductive layer and a free magnetic layerdeposited thereon; a bias layer to align a magnetic direction of saidfree magnetic layer in a direction perpendicular to the magneticdirection of said pinned magnetic layer; and an electrode layer to applya sensing current into said pinned magnetic layer, said non-magneticelectrically conductive layer, and said free magnetic layer, whereinsaid antiferromagnetic layer, said pinned magnetic layer, and saidnon-magnetic electrically conductive layer extend to regions beside bothsides of said free magnetic layer, said bias layer is formed on saidnon-magnetic electrically conductive layer in said regions beside bothsides of said free magnetic layer while said non-magnetic electricallyconductive layer is disposed between said pinned magnetic layer and saidbias layer such that said pinned magnetic layer is magnetically shieldedfrom said bias layer, said electrode layer is formed on said bias layer,and each side of said free magnetic layer contacts a corresponding biaslayer such that a bias magnetic field from said bias layer is applied tosaid free magnetic layer.
 2. A spin-valve magnetoresistive elementaccording to claim 1, wherein a non-magnetic metal layer having abody-centered cubic structure and (100) orientation is formed betweensaid non-magnetic electrically conductive layer and said bias layer. 3.A spin-valve magnetoresistive element according to claim 2, wherein saidmetal layer comprises Cr, Ti, Mo, or W₅₀ Mo₅₀.